FLUOROELASTOMER COMPOSITION

Description

Cross-reference to Related Application

[0001] This application claims priority to European application No. 16179972.1 filed July 18, 2016, the whole content of this application being incorporated herein by reference for all purposes.

Technical Field

[0002] The invention pertains to a fluoroelastomer composition able to provide for cured parts having improved thermal and steam resistance, to a method of curing the same and to cured articles obtained therefrom.

Background Art

[0003] Fluoroelastomers, and more specifically perfluoroelastomers, have long been used in a variety of applications that require excellent resistance to high temperature and chemical attack.

[0004] To enable crosslinking of these fluoroelastomers, it has been long known to incorporate in the fluoroelastomer polymer chain a small percentage of monomers including nitrile groups, whose reactivity in the presence of a variety of curing agents, including notably aromatic tetra-amines, di(amino(thio)phenols), and organo-tin compounds, including tetraalkyl and tetraaryl compounds, is such to provide crosslinking point of supposedly triazine-type or similar structure, possessing high thermal stability, and certainly higher than stability of bridging/crosslinking groups provided by alternative crosslinking chemistry.

[0005] For this reason, nitrile-cure site containing fluoroelastomers have been long recognized for their thermal stability; within this area, dual cure approaches have been already pursued in the past for further improving e.g. curing rate.

[0006] Notably, US 5447993 05.09.1995 discloses nitrile-containing perfluoroelastomers which are cured by a combination of a peroxide, a co-agent, which can be a diene or a triene, and a catalyst causing crosslinks to form using nitrile groups, for achieving faster cure rate, while maintaining good thermal properties in vulcanizates. According to this document, two distinct (chemical) cure processes are believed to take place, one caused by the peroxide and the polyunsaturated co-agent, and the other caused by a catalysed reaction of nitrile groups.

[0007] US 2015073111 (E.I. DUPONT DE NEMOURS & CIE) 12.03.2015 is directed to certain VDF-based fluoroelastomers comprising secondary cyano-groups, which can be cured using, as curatives, diaminobisphenol AF, ammonia generators such as urea, and free radical systems such as the combination of an organic peroxide with a multifunctional coagent such as triallylisocyanurate.

[0008] EP 0606883 A (NIPPON MEKTRON) 20.07.1994 pertains to a composition including a nitrile-containing fluoroelastomer and a bisaminophenol derivative curing agent.

[0009] EP 0661304 A (SOLVAY SPECIALTY POLYMERS ITALY SPA) 05.07.1995 is directed to iodine-containing fluoroelastomers comprising recurring units derived from a bis-olefin, which are notably cured via peroxidic route using a combination of a peroxide and curing co-agents, among which triallylisocyanurate is specifically mentioned as preferred, and used in all exemplified embodiments.

[0010] In this area, there remains a continuous quest for curable fluoroelastomer compositions able to deliver upon curing even improved thermal and steam resistance.

Summary of invention

[0011] A first object of the invention is hence a fluoroelastomer composition [composition (C)] comprising:

• at least one fluoroelastomer [fluoroelastomer (A)] comprising from 0.1 to 10.0 % moles of recurring units derived from at least one cure-site containing monomer having at least a nitrile group [monomer (CSM)], with respect to total moles of recurring units, and comprising iodine and/or bromine cure sites in an amount such that the I and/or Br content is of from 0.04 to 10.0% wt, with respect to the total weight of fluoroelastomer (A);
• at least an organic peroxide [peroxide (O)];
• at least one bis-olefin [bis-olefin (OF)] having general formula :
  
  wherein R₁, R₂, R₃, R₄, R₅ and R₆, equal or different from each other, are H or C₁-C₅ alkyl; Z is a linear or branched C₁-C₁₈ (hydro)carbon radical (including alkylene or cycloalkylene radical), optionally containing oxygen atoms, preferably at least partially fluorinated, or a (per)fluoro(poly)oxyalkylene radical comprising one or more catenary ethereal bonds.
  and
• at least one compound [compound (A)] selected from the group consisting of:

  (A- 1) bis-amino(thio)phenol compounds [aminophenol (AP)] of formula:
  
  wherein:

  • A is a bond, -SO₂-, -O-, -C(O)-, or a (fluoro)alkyl of 1 to 10 carbon atoms (specifically a perfluoroalkyl of 1 to 10 carbon atoms);
  • each of E, equal of different at each occurrence, is oxygen or sulphur, preferably oxygen, and wherein the amino and -EH groups are interchangeably in ortho, meta or para positions with respect to the group A;

  (A-2) aromatic tetraamine compounds [amine (TA)] of formula:
  
  wherein:

  • A' is a bond, -SO₂-, -O-, -C(O)-, (fluoro)alkyl of 1 to 10 carbon atoms (specifically a perfluoroalkyl of 1 to 10 carbon atoms);
  • each of R_N, equal to or different from each other, is a hydrogen atom or a C₁-C₁₂ hydrocarbon group, preferably an aryl group; and
  • the amino groups are interchangeably in ortho, meta or para positions with respect to the group A'.

[0012] The Applicant has surprisingly found that when combining the afore-mentioned dual-cure system, including a compound (A), as above detailed, a peroxide and a bis-olefin, an iodine/bromine containing fluoroelastomer comprising nitrile cure sites can be cured so as to deliver significantly improved steam resistance combined with thermal resistance, specifically substantially improved over performances associated to compounds cured by single "nitrile"-curing and even over performances associated to compounds submitted to dual cure, but in the presence of alternative polyunsaturated compounds.

Detailed description of the invention

[0013] The composition (C) comprises one or more than one compound (A), as above detailed.

[0014] The aminophenol (AP) can be selected from the group consisting of 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)-ethylidene]bis(2-aminophenol); and 4,4'-sulfonylbis(2-aminophenol); the amine (TA) can be selected from the group consisting of 3,3'-diaminobenzidine, 3,3',4,4'-tetraaminobenzophenone and a compound of formula:

[0015] According to certain preferred embodiments, compound (A) of the composition (C) is at least one aminophenol (AP). According to these embodiments, particularly preferred is 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)-ethylidene]bis(2-aminophenol), otherwise known as bis-aminophenol AF, having formula:

[0016] The amount of compound (A) in the composition (C) is generally of at least 0.1, preferably at least 0.2, more preferably at least 0.5 and/or generally at most 10 phr, preferably at most 6 phr, more preferably at most 5 phr, relative to 100 weight parts of fluoroelastomer (A).

[0017] The bis-olefin (OF) is preferably selected from the group consisting of those complying with formulae (OF-1), (OF-2) and (OF-3) :

(OF-1)

wherein j is an integer between 2 and 10, preferably between 4 and 8, and R1, R2, R3, R4, equal or different from each other, are H, F or C_1-5 alkyl or (per)fluoroalkyl group;

(OF-2)

wherein each of A, equal or different from each other and at each occurrence, is independently selected from F, Cl, and H; each of B, equal or different from each other and at each occurrence, is independently selected from F, Cl, H and OR_B, wherein R_B is a branched or straight chain alkyl radical which can be partially, substantially or completely fluorinated or chlorinated; E is a divalent group having 2 to 10 carbon atom, optionally fluorinated, which may be inserted with ether linkages; preferably E is a -(CF₂)_m- group, with m being an integer from 3 to 5; a preferred bis-olefin of (OF-2) type is F₂C=CF-O-(CF₂)₅-O-CF=CF₂.

(OF-3)

wherein E, A and B have the same meaning as above defined; R5, R6, R7, equal or different from each other, are H, F or C_1-5 alkyl or (per)fluoroalkyl group.

[0018] Bis-olefins (OF) which have been found particularly effective are those of type (OF-1) as above detailed, and more specifically particularly good results have been obtained with a bis-olefin (OF) of formula: CH₂=CH-(CF ₂)₆-CH=CH₂.

[0019] The amount of bis-olefin (OF) in the composition (C) is generally of at least 0.1, preferably at least 0.2, more preferably at least 0.5 and/or generally at most 10 phr, preferably at most 6 phr, more preferably at most 5 phr, relative to 100 weight parts of fluoroelastomer (A).

[0020] For the purposes of this invention, the term "(per)fluoroelastomer" [fluoroelastomer (A)] is intended to designate a fluoropolymer resin serving as a base constituent for obtaining a true elastomer, said fluoropolymer resin comprising more than 10 % wt, preferably more than 30 % wt, of recurring units derived from at least one ethylenically unsaturated monomer comprising at least one fluorine atom (hereafter, (per)fluorinated monomer) and, optionally, recurring units derived from at least one ethylenically unsaturated monomer free from fluorine atom (hereafter, hydrogenated monomer) .

[0021] True elastomers are defined by the ASTM, Special Technical Bulletin, No. 184 standard as materials capable of being stretched, at room temperature, to twice their intrinsic length and which, once they have been released after holding them under tension for 5 minutes, return to within 10 % of their initial length in the same time.

[0022] Generally fluoroelastomer (A) comprises recurring units derived from at least one (per)fluorinated monomer, in addition to recurring units derived from monomer (CSM), as above detailed, wherein said (per)fluorinated monomer is generally selected from the group consisting of:

• C₂-C₈ fluoro- and/or perfluoroolefins, such as tetrafluoroethylene (TFE), hexafluoropropene (HFP), pentafluoropropylene, and hexafluoroisobutylene;
• C₂-C₈ hydrogenated monofluoroolefins, such as vinyl fluoride; 1,2-difluoroethylene, vinylidene fluoride (VDF) and trifluoroethylene (TrFE);
• (per)fluoroalkylethylenes complying with formula CH₂=CH-R_f0, in which R_f0 is a C₁-C₆ (per)fluoroalkyl or a C₁-C₆ (per)fluorooxyalkyl having one or more ether groups ;
• chloro- and/or bromo- and/or iodo-C₂-C₆ fluoroolefins, like chlorotrifluoroethylene (CTFE);
• fluoroalkylvinylethers complying with formula CF₂=CFOR_f1 in which R _f1 is a C₁-C₆ fluoro- or perfluoroalkyl, e.g. -CF₃, -C₂F₅, -C₃F₇ ;
• hydrofluoroalkylvinylethers complying with formula CH₂=CFOR_f1 in which R_f1 is a C₁-C₆ fluoro- or perfluoroalkyl, e.g. -CF₃, -C₂F₅, -C₃F₇ ;
• fluoro-oxyalkylvinylethers complying with formula CF₂=CFOX₀, in which X₀ is a C₁-C₁₂ oxyalkyl, or a C₁-C₁₂ (per)fluorooxyalkyl having one or more ether groups; in particular (per)fluoro-methoxy-vinylethers complying with formula CF₂=CFOCF₂OR_f2 in which R_f2 is a C₁-C₆ fluoro- or perfluoroalkyl, e.g. -CF₃, -C₂F₅, -C₃F₇ or a C₁-C₆ (per)fluorooxyalkyl having one or more ether groups, like -C₂F₅-O-CF₃;
• functional fluoro-alkylvinylethers complying with formula CF₂=CFOY₀, in which Y₀ is a C₁-C₁₂ alkyl or (per)fluoroalkyl, or a C₁-C₁₂ oxyalkyl or a C₁-C₁₂ (per)fluorooxyalkyl, said Y₀ group comprising a carboxylic or sulfonic acid group, in its acid, acid halide or salt form;
• (per)fluorodioxoles, of formula :
  
  wherein each of R_f3, R_f4, R_f5, R_f6, equal to or different from each other, is independently a fluorine atom, a C₁-C₆ fluoro- or per(halo)fluoroalkyl, optionally comprising one or more oxygen atom, e.g. -CF₃, -C₂F₅, -C₃F ₇, -OCF₃, -OCF₂CF₂OCF₃.

[0023] Examples of hydrogenated monomers are notably hydrogenated alpha-olefins, including ethylene, propylene, 1-butene, diene monomers, styrene monomers, alpha-olefins being typically used.

[0024] Fluoroelastomers (A) are in general amorphous products or products having a low degree of crystallinity (crystalline phase less than 20 % by volume) and a glass transition temperature (T_g) below room temperature. In most cases, the fluoroelastomer (A) has advantageously a T_g below 10°C, preferably below 5°C, more preferably 0°C.

[0025] The fluoroelastomer (A) is preferably selected among:

(1) VDF-based copolymers, in which VDF is copolymerized with monomer (CSM), as above detailed, and at least one additional comonomer selected from the group consisting of :

(a) C₂-C₈ perfluoroolefins , such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP);

(b) hydrogen-containing C₂-C₈ olefins, such as vinyl fluoride (VF), trifluoroethylene (TrFE), hexafluoroisobutene (HFIB), perfluoroalkyl ethylenes of formula CH₂ = CH-R_f, wherein R_f is a C₁-C₆ perfluoroalkyl group;

(c) C₂-C₈ fluoroolefins comprising at least one of iodine, chlorine and bromine, such as chlorotrifluoroethylene (CTFE);

(d) (per)fluoroalkylvinylethers (PAVE) of formula CF₂ = CFOR_f, wherein R_f is a C₁-C₆ (per)fluoroalkyl group, preferably CF₃, C₂F₅, C₃F₇;

(e) (per)fluoro-oxy-alkylvinylethers of formula CF₂ = CFOX, wherein X is a C₁-C₁₂ ((per)fluoro)-oxyalkyl comprising catenary oxygen atoms, e.g. the perfluoro-2-propoxypropyl group;

(f) (per)fluorodioxoles having formula :

wherein each of R_f3, R_f4, R_f5, R_f6, equal to or different from each other, is independently selected from the group consisting of fluorine atom and C₁ -C₆ (per)fluoroalkyl groups, optionally comprising one or more than one oxygen atom, such as notably -CF₃, -C₂F₅, -C₃F₇, -OCF₃, -OCF₂CF₂OCF ₃; preferably, perfluorodioxoles;

(g) (per)fluoro-methoxy-vinylethers (MOVE, hereinafter) having formula:

        CF₂=CFOCF₂OR_f2

wherein R_f2 is selected from the group consisting of C₁-C₆ (per)fluoroalkyls; C₅-C₆ cyclic (per)fluoroalkyls; and C₂-C₆ (per)fluorooxyalkyls, comprising at least one catenary oxygen atom; R_f2 is preferably -CF₂CF₃ (MOVE1); -CF₂CF₂OCF₃ (MOVE2); or -CF₃ (MOVE3);

(h) C₂-C₈ non-fluorinated olefins (Ol), for example ethylene and propylene; and

(2) TFE-based copolymers, in which TFE is copolymerized with monomer (CSM), as above detailed, and at least one additional comonomer selected from the group consisting of (c), (d), (e), (g), (h) and (i) as above detailed .

[0026] Fluoroelastomer (A) is generally selected among TFE-based copolymers, as above detailed.

[0027] Optionally, fluoroelastomer (A) of the present invention may also comprises recurring units derived from a bis-olefin [bis-olefin (OF)], as above detailed.

[0028] Among cure-site containing monomers of type (CSM), as above detailed, comprised in fluoroelastomer (A), preferred monomers are (per)fluorinated and are especially those selected from the group consisting of:

(CSM-1) perfluorovinyl ethers containing nitrile groups of formula CF₂ =CF-(OCF₂CFX^CN)_m-O-(CF₂)_n-CN, with X^CN being F or CF₃, m being 0, 1, 2, 3 or 4; n being an integer from 1 to 12;

(CSM-2) perfluorovinyl ethers containing nitrile groups of formula CF₂ =CF-(OCF₂CFX^CN)_m'-O-CF₂-CF(CF₃)-CN, with X^CN being F or CF₃, m' being 0, 1, 2, 3 or 4.

[0029] Specific examples of cure-site containing monomers of type CSM-1 and CSM-2 suitable to the purposes of the present invention are notably those described in patents US 4281092 (DU PONT) 28.07.1981 , , US 5447993 (DU PONT) 05.09.1995 and US 5789489 (DU PONT) 04.08.1998 .

[0030] Preferred cure-site monomer is perfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene) of formula: CF₂=CF-O-CF ₂-CF(CF₃)-O-CF₂-CF₂-CN (8-CNVE).

[0031] As said, fluoroelastomer (A) comprises iodine and/or bromine cure sites.

[0032] These iodine and/or bromine cure sites might be comprised as pending groups bound to the backbone of the fluoroelastomer (A) polymer chain or might be comprised as terminal groups of said polymer chain.

[0033] According to a first embodiment, the iodine and/or bromine cure sites are comprised as pending groups bound to the backbone of the fluoroelastomer (A) polymer chain; the fluoroelastomer (A) according to this embodiment typically comprises recurring units derived from brominated and/or iodinated cure-site comonomers selected from:

• bromo and/or iodo alpha-olefins containing from 2 to 10 carbon atoms such as bromotrifluoroethylene or bromotetrafluorobutene described, for example, in US 4035565 (DU PONT) 12.07.1977 or other compounds bromo and/or iodo alpha-olefins disclosed in US 4694045 (DU PONT) 15.09.1987 ;
• iodo and/or bromo fluoroalkyl vinyl ethers (as notably described in patents US 4564662 (MINNESOTA MINING & MFG [US]) 14.01.1986 and EP 199138 A (DAIKIN IND LTD) 29.10.1986).

[0034] According to a second preferred embodiment, the iodine and/or bromine cure sites (preferably iodine cure sites) are comprised as terminal groups of the fluoroelastomer (A) polymer chain; the fluoroelastomer according to this embodiment is generally obtained by addition to the polymerization medium during fluoroelastomer (A) manufacture of at least one of:

• iodinated and/or brominated chain-transfer agent(s); suitable chain-chain transfer agents are typically those of formula R_f(I)_x(Br)_y, in which R_f is a (per)fluoroalkyl or a (per)fluorochloroalkyl containing from 1 to 8 carbon atoms, while x and y are integers between 0 and 2, with 1 ≤ x+y ≤ 2 (see, for example, patents US 4243770 (DAIKIN IND LTD) 06.01.1981 and US 4943622 (NIPPON MEKTRON KK) 24.07.1990); and
• alkali metal or alkaline-earth metal iodides and/or bromides, such as described notably in patent US 5173553 (AUSIMONT SRL) 22.12.1992 .

[0035] Advantageously, for ensuring acceptable reactivity it is generally understood that the content of iodine and/or bromine in the fluoroelastomer (A) should be of at least 0.05 % wt, preferably of at least 0.06 % weight, with respect to the total weight of fluoroelastomer (A).

[0036] On the other side, amounts of iodine and/or bromine not exceeding preferably 7 % wt, more specifically not exceeding 5 % wt, or even not exceeding 4 % wt, with respect to the total weight of fluoroelastomer (A), are those generally selected for avoiding side reactions and/or detrimental effects on thermal stability.

[0037] Exemplary fluoroelastomers (A) which can be used in the composition of the present invention are those having iodine cure sites comprised as terminal groups and having following monomers composition (in mol %, with respect to the total moles of recurring units) :

(i) tetrafluoroethylene (TFE): 50-80 %; (per)fluoroalkylvinylethers (PAVE): 15-50 %; monomer (CSM): 0.1-10 %; bis-olefin (OF): 0-5 %;

(ii) tetrafluoroethylene (TFE): 20-70 %; (per)fluoro-methoxy-vinylethers (MOVE): 25-75 %; (per)fluoroalkylvinylethers (PAVE): 0-50 %; monomer (CSM) 0.1-10 %; bis-olefin (OF): 0-5 %.

[0038] The composition (C) further comprises at least an organic peroxide [peroxide (O)]; the choice of the said peroxide (O) is not particularly critical provided that the same is capable of generating radicals by thermal decomposition. Among most commonly used peroxides, mention can be made of di(alkyl/alryl) peroxides, including for instance di-tert-butyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, di(t-butylperoxyisopropyl)benzene, dicumyl peroxide; diacyl peroxides, including dibenzoyl peroxide, disuccinic acid peroxide, di(4-methylbenzoyl)peroxide, di(2,4-dichlorobenzoyl)peroxide, dilauroyl peroxide, decanoyl peroxide; percarboxylic acids and esters, including di-tert-butyl perbenzoate, t-butylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane; peroxycarbonates including notably di(4-t-butylcyclohexyl)peroxydicarbonate, di(2-phenoxyethyl)peroxydicarbonate, bis[1,3-dimethyl-3-(tert-butylperoxy)butyl] carbonate, t-hexylperoxyisoproprylcarbonate, t-butylperoxyisopropylcarbonate. Other suitable peroxide systems are those described, notably, in patent applications EP 136596 A (MONTEDISON SPA) 10.04.1985 and EP 410351 A (AUSIMONT SRL) 30.01.1991 , whose content is hereby incorporated by reference.

[0039] Choice of the most appropriate peroxide depending upon curing conditions (time, temperature) will be done by one of ordinary skills in the art considering notably ten-hours half time temperature of the peroxide (O).

[0040] The amount of peroxide (O) in the composition (C) is generally of 0.1 to 5 phr, preferably of 0.2 to 4 phr, relative to 100 weight parts of fluoroelastomer (A).

[0041] The composition (C) may further additionally comprise ingredients which maybe commonly used for the peroxide curing of fluoroelastomers; more specifically, composition (C) may generally further comprise (a) one or more than one metallic basic compound, in amounts generally of from 0.5 to 15 phr, and preferably of from 1 to 10 phr, relative to 100 weight parts of fluoroelastomer (A); metallic basic compounds are generally selected from the group consisting of (j) oxides or hydroxides of divalent metals, for instance oxides or hydroxides of Mg, Zn, Ca or Pb, and (jj) metal salts of a weak acid, for instance Ba, Na, K, Pb, Ca stearates, benzoates, carbonates, oxalates or phosphites; (b) one or more than one acid acceptor which is not a metallic basic compound, in amounts generally of from 0.5 to 15 phr, and preferably of from 1 to 10 phr, relative to 100 weight parts of fluoroelastomer (A); these acid acceptors are generally selected from nitrogen-containing organic compounds, such as 1,8-bis(dimethylamino)naphthalene, octadecylamine, etc., as notably described in EP 708797 A (DU PONT) 01.05.1996 ; (c) other conventional additives, such as fillers, thickeners, pigmen-ts, antioxidants, stabilizers, processing aids, and the like.

[0042] The invention also pertains to a method for fabricating shaped articles comprising curing the composition (C), as above described.

[0043] The composition (C) can be fabricated, e.g. by moulding (injection moulding, extrusion moulding), calendering, or extrusion, into the desired shaped article, which is advantageously subjected to vulcanization (curing) during the processing itself and/or in a subsequent step (post-treatment or post-cure), advantageously transforming the relatively soft, weak, fluoroelastomeric uncured composition into a finished article made of non-tacky, strong, insoluble, chemically and thermally resistant cured fluoroelastomer material.

[0044] Yet, the invention pertains to cured articles obtained from the composition (C), as above detailed. Said cured articles are generally obtained by moulding and curing the fluoroelastomer composition, as above detailed. These cured articles may be sealing articles, including O(square)-rings, packings, gaskets, diaphragms, shaft seals, valve stem seals, piston rings, crankshaft seals, cam shaft seals, and oil seals or maybe piping and tubings, in particular flexible hoses or other items, including conduits for delivery of hydrocarbon fluids and fuels.

[0045] Cured articles obtained from the composition (C), thanks to their outstanding thermal and water vapour resistance, are suitable for being used in fields of endeavours wherein extremely demanding conditions of use are combined with exposure to water vapour, e.g. for use in the oil and gas market as seals, components and sealing elements, gaskets, hoses, tubings.

[0046] Further in addition, the invention pertains to a method for processing the composition (C), as above detailed, according any of injection moulding, compression moulding, extrusion moulding, coating, screen printing technique, form-in-place technique.

[0047] Should the disclosure of any of the patents, patent applications, and publications that are incorporated herein by reference conflict with the present description to the extent that it might render a term unclear, the present description shall take precedence.

[0048] The present invention will be now described in more detail with reference to the following examples, whose purpose is merely illustrative and not limitative of the scope of the invention.

EXAMPLES

Manufacture of nitrile-containing fluoroelastomer

EXAMPLE 1

[0049] In a 5 litres reactor equipped with a mechanical stirrer operating at 630 rpm, 3.1 l of demineralized water and 31 ml of a microemulsion, previously obtained by mixing 7.4 ml of a perfluoropolyoxyalkylene having acidic end groups of formula: CF₂ClO(CF₂-CF(CF₃)O)_n(CF₂O)_mCF₂COOH, wherein n/m = 10, having average molecular weight of 600, 1.9 ml of a 30 % v/v NH4OH aqueous solution, 17.4 ml of demineralised water and 4.3 ml of GALDEN® D02 perfluoropolyether of formula:

        C-F_-3-O(CF₂CF(CF₃)O)_n(CF₂O)_mCF₃

with n/m = 20, having average molecular weight of 450, were introduced.

[0050] Then 2.5 g of 1,4-diiodoperfluorobutane (C₄F₈I₂) as chain transfer agent were introduced, and the reactor was heated and maintained at a set-point temperature of 80°C; a mixture of tetrafluoroethylene (TFE) (38% moles) and perfluoromethylvinylether (MVE) (62% moles) was then added to reach a final pressure of 21 bar (2.1 MPa). 0.31 g of ammonium persulfate (APS) as initiator were then introduced. Pressure was maintained at set-point of 21 bar by continuous feeding of a gaseous mixture of TFE (60% moles) and MVE (40% moles) up to a total of 1350 g, and 129 g of 8-CNVE in 20 portions each 5% increase in conversion, starting from the beginning of the polymerization, were fed to the reactor. Moreover, 0.16 g of APS at 15%, 40% and 55% conversion of gaseous mixture, were introduced. Then the reactor was cooled, vented and the latex recovered. The latex was coagulated with nitric acid as a coagulation agent, and the polymer separated from the aqueous phase, washed with demineralised water and dried in a convection oven at 120°C for 24 hours.

[0051] The composition of the obtained polymer from NMR analysis was found to be: TFE 64.6 %mol, MVE 34.2 %mol, 8-CNVE 1.2 %mol, and the Mooney viscosity at 121°C is 64 MU.

General compounding and curing procedure

[0052] The fluoroelastomer of Ex. 1 was compounded with the ingredients as detailed below in a two rolls open mill. Plaques were cured in a pressed mould and then post-treated in an air circulating oven in conditions detailed in Table below.

[0053] Cure behaviour was characterized by Moving Die Rheometer (MDR), in conditions as specified below, by determining the following properties:

M_L = Minimum torque (lb x in)

M_H = Maximum torque (lb x in)

t_S2 = Scorch time, time for two units rise from M_L (sec);

t₀₂ = Time to 2% state of cure (sec);

t₅₀ = Time to 50% state of cure (sec);

t₉₀ = Time to 90% state of cure (sec);

t₉₅ = Time to 95% state of cure (sec).

[0054] The tensile properties have been determined on specimens punched out from the plaques, according to the ASTM D 412 C Standard, after post-cure and after exposure to overheated water vapour at 220°C or 250°C.
TS is the tensile strength in MPa;
M₁₀₀ is the modulus in MPa at an elongation of 100 %;
E.B. is the elongation at break in %.

[0055] Variation of properties (including weight change, volume swell and mechanical properties) upon exposure to steam are recollected as percentage over the corresponding values of the properties as determined on cured sample after post-cure. The value "specimens destroyed" ("D" in table 3, herein below) means specimen was destroyed upon exposure, so that no meaningful determination was possible.

[0056] Compression set (CS) values have been determined on O-rings (#214 class) according to the ASTM D 395-B method at temperatures ranging from 200°C to 300°C; values in the table are the average of determinations made on 4 specimens. The value "specimens destroyed" ("D" in table 3, herein below) means that all specimens were destroyed upon compression in indicated conditions, so that no measurement of % deformation was possible.

[0057] Curing recipe and conditions and properties of cured sample, before and after exposure to water vapour at 220°C or 250°C are summarized, respectively, in tables 1 to 3.

Table 1

Ingredient		Ex.1C	Ex.2	Ex.3	Ex. 4C
FKM from Ex. 1	Wt parts	100	100	100	100
BOAP(*)	phr	2.00	2.00	1.00	2.00
Bis-Olefin(#)	phr		0.75	0.75
Peroxide($)	phr		0.50	0.50	0.50
C-black(^)	phr	20.00	20.00	20.00	20.00
TAIC(§)	phr				0.70

(*)BOAP: bis-aminophenol AF, commercially available from Apollo Scientific; (#) Bis-Olefin: of formula CH2=CH-(CF2)6-CH=CH2; ($)Peroxide: neat 2,5-dimethyl-2,5-di-t-butyl-peroxy-hexane, commercially available from Arkema under tradename Luperox® 101; (§)TAIC: Triallyl isocyanurate (75 %) dispersion in silica, commercially available as Drimix TAIC 75 from Finco.

Table 2

Sample		Ex.1C	Ex.2	Ex.3	Ex.4C
ML	(Nxm)	1.0	0.9	0.8	0.3
MH	(Nxm)	18.7	17.7	15.8	23.8
ts2	(s)	230.0	166.0	122.0	104.0
t02	(s)	92.0	71.0	51.0	65.0
t50	(s)	443.0	404.0	336.0	535.0
t90	(s)	678.0	635.0	569.0	1182.0
t95	(s)	731.0	677.0	610.0	1337.0

Molding Conditions
Time and T in the press		10 min at 170°C	10 min at 170°C	10 min at 170°C	10 min at 170°C

Post-cure conditions
In air oven		(8+16h) at 290°C	(8+16h) at 290°C	(8+16h) at 290°C	(8+16h) at 290°C

Table 3

Property		Ex.1C	Ex.2	Ex.3	Ex.4C
Properties after post-cure
TS	(MPa)	13.9	14.2	13.8	14.3
M100	(MPa)	9.8	8.5	7.6	10.2
E.B.	(%)	117	126	131	120
CS (70h at 200°C)	(%)	6	9	13	12
CS (70h at 300°C)	(%)	D	29	28	30
CS (70h at 315°C)	(%)	D	D	42	D

After exposure to steam at 220°C for 168 hours
ΔTS	(%)	D	-27	-6	-49
ΔM100	(%)	D	-34	-14	-67
ΔE.B.	(%)	D	45	1	165
Δweight	(%)	D	-0.2	0.9	0.3
Δvolume	(%)	D	0.0	1.7	0.7

After exposure to steam at 250°C for 168 hours
ΔTS	(%)	D	-48	-33	-63
ΔM100	(%)	D	-56	-24	-74
ΔE.B.	(%)	D	87	9	214
Δweight	(%)	D	-0.4	0.4	0.3
Δweight	(%)	D	0.0	0.7	0.7

Claims

1. A fluoroelastomer composition [composition (C)] comprising:

- at least one fluoroelastomer [fluoroelastomer (A)] comprising from 0.1 to 10.0 % moles of recurring units derived from at least one cure-site containing monomer having at least a nitrile group [monomer (CSM)], with respect to total moles of recurring units, and comprising iodine and/or bromine cure sites in an amount such that the I and/or Br content is of from 0.04 to 10.0% wt, with respect to the total weight of fluoroelastomer (A);

- at least an organic peroxide [peroxide (O)];

- at least one bis-olefin [bis-olefin (OF)] having general formula :

wherein R₁, R₂, R₃, R₄, R₅ and R₆, equal or different from each other, are H or C₁-C₅ alkyl; Z is a linear or branched C₁-C₁₈ (hydro)carbon radical (including alkylene or cycloalkylene radical), optionally containing oxygen atoms, preferably at least partially fluorinated, or a (per)fluoro(poly)oxyalkylene radical comprising one or more catenary ethereal bonds.
and

- at least one compound [compound (A)] selected from the group consisting of:

(A- 1) bis-amino(thio)phenol compounds [aminophenol (AP)] of formula:

wherein:

- A is a bond, -SO₂-, -O-, -C(O)-, or a (fluoro)alkyl of 1 to 10 carbon atoms (specifically a perfluoroalkyl of 1 to 10 carbon atoms);

- each of E, equal of different at each occurrence, is oxygen or sulphur, preferably oxygen, and wherein the amino and -EH groups are interchangeably in ortho, meta or para positions with respect to the group A; and

(A-2) aromatic tetraamine compounds [amine (TA)] of formula:

wherein:

- A' is a bond, -SO₂-, -O-, -C(O)-, (fluoro)alkyl of 1 to 10 carbon atoms (specifically a perfluoroalkyl of 1 to 10 carbon atoms);

- each of R_N, equal to or different from each other, is a hydrogen atom or a C₁

- C₁₂ hydrocarbon group, preferably an aryl group; and

- the amino groups are interchangeably in ortho, meta or para positions with respect to the group A'.

2. The composition (C) of Claim 1, wherein the aminophenol (A) is selected from the group consisting of 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)-ethylidene]bis(2-aminophenol) and 4,4'-sulfonylbis(2-aminophenol); and/or wherein the amine (TA) is selected from the group consisting of 3,3'-diaminobenzidine, and 3,3',4,4'-tetraaminobenzophenone and a compound of formula:

3. The composition (C) according to anyone of the preceding claims, wherein the amount of compound (A) in the composition (C) is of at least 0.1, preferably at least 0.2, more preferably at least 0.5; and/or at most 10 phr, preferably at most 6 phr, more preferably at most 5 phr, relative to 100 weight parts of fluoroelastomer (A).

4. The composition (C) of anyone of the preceding claims, wherein the bis-olefin (OF) is selected from the group consisting of those complying with formulae (OF-1), (OF-2) and (OF-3) :

(OF-1)

wherein j is an integer between 2 and 10, preferably between 4 and 8, and R1, R2, R3, R4, equal or different from each other, are H, F or C_1-5 alkyl or (per)fluoroalkyl group;

(OF-2)

wherein each of A, equal or different from each other and at each occurrence, is independently selected from F, Cl, and H; each of B, equal or different from each other and at each occurrence, is independently selected from F, Cl, H and OR_B, wherein R_B is a branched or straight chain alkyl radical which can be partially, substantially or completely fluorinated or chlorinated; E is a divalent group having 2 to 10 carbon atom, optionally fluorinated, which may be inserted with ether linkages; preferably E is a -(CF₂)_m- group, with m being an integer from 3 to 5; a preferred bis-olefin of (OF-2) type is F₂C=CF-O-(CF₂)₅ -O-CF=CF₂.

(OF-3)

wherein E, A and B have the same meaning as above defined; R5, R6, R7, equal or different from each other, are H, F or C_1-5 alkyl or (per)fluoroalkyl group.

5. The composition (C) of claim 4, wherein the bis-olefin (OF) complies with formula: CH₂=CH-(CF₂)₆-CH=CH_2.

6. The composition (C) according to anyone of the preceding claims, wherein the amount of bis-olefin (OF) in the composition (C) is of at least 0.1, preferably at least 0.2, more preferably at least 0.5 and/or at most 10 phr, preferably at most 6 phr, more preferably at most 5 phr, relative to 100 weight parts of fluoroelastomer (A).

7. The composition of anyone of preceding claims, wherein fluoroelastomer (A) comprises recurring units derived from at least one (per)fluorinated monomer, in addition to recurring units derived from monomer (CSM), as above detailed, wherein said (per)fluorinated monomer is generally selected from the group consisting of:

- C₂-C₈ fluoro- and/or perfluoroolefins, such as tetrafluoroethylene (TFE), hexafluoropropene (HFP), pentafluoropropylene, and hexafluoroisobutylene;

- C₂-C₈ hydrogenated monofluoroolefins, such as vinyl fluoride;

- 1,2-difluoroethylene, vinylidene fluoride (VDF) and trifluoroethylene (TrFE);

- (per)fluoroalkylethylenes complying with formula CH₂=CH-R_f0, in which R_f0 is a C₁-C₆ (per)fluoroalkyl or a C₁-C₆ (per)fluorooxyalkyl having one or more ether groups ;

- chloro- and/or bromo- and/or iodo-C₂-C₆ fluoroolefins, like chlorotrifluoroethylene (CTFE);

- fluoroalkylvinylethers complying with formula CF₂=CFOR_f1 in which R_f1 is a C ₁-C₆ fluoro- or perfluoroalkyl, e.g. -CF₃, -C₂F₅, -C₃F₇ ;

- hydrofluoroalkylvinylethers complying with formula CH₂=CFOR_f1 in which R_f1 is a C₁-C₆ fluoro- or perfluoroalkyl, e.g. -CF₃, -C₂F₅, -C₃F₇;

- fluoro-oxyalkylvinylethers complying with formula CF₂=CFOX₀, in which X₀ is a C₁-C₁₂ oxyalkyl, or a C₁-C₁₂ (per)fluorooxyalkyl having one or more ether groups; in particular (per)fluoro-methoxy-vinylethers complying with formula CF ₂=CFOCF₂OR_f2 in which R_f2 is a C₁-C₆ fluoro- or perfluoroalkyl, e.g. -CF₃, -C₂ F₅, -C₃F₇ or a C₁-C₆ (per)fluorooxyalkyl having one or more ether groups, like -C₂F₅-O-CF₃;

- functional fluoro-alkylvinylethers complying with formula CF₂=CFOY₀, in which Y₀ is a C₁-C₁₂ alkyl or (per)fluoroalkyl, or a C₁-C₁₂ oxyalkyl or a C₁-C₁₂ (per)fluorooxyalkyl, said Y₀ group comprising a carboxylic or sulfonic acid group, in its acid, acid halide or salt form;

- (per)fluorodioxoles, of formula :

wherein each of R_f3, R_f4, R_f5, R_f6, equal to or different from each other, is independently a fluorine atom, a C₁-C₆ fluoro- or per(halo)fluoroalkyl, optionally comprising one or more oxygen atom, e.g. -CF₃, -C₂F₅, -C₃F₇, -OCF ₃, -OCF₂CF₂OCF₃.

8. The composition (C) of anyone of the preceding claims, wherein the fluoroelastomer (A) is selected among:

(1) VDF-based copolymers, in which VDF is copolymerized with monomer (CSM), as above detailed, and at least one additional comonomer selected from the group consisting of:

(a) C₂-C₈ perfluoroolefins , such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP);

(b) hydrogen-containing C₂-C₈ olefins, such as vinyl fluoride (VF), trifluoroethylene (TrFE), hexafluoroisobutene (HFIB), perfluoroalkyl ethylenes of formula CH₂ = CH-R_f, wherein R_f is a C₁-C₆ perfluoroalkyl group;

(c) C₂-C₈ fluoroolefins comprising at least one of iodine, chlorine and bromine, such as chlorotrifluoroethylene (CTFE);

(d) (per)fluoroalkylvinylethers (PAVE) of formula CF₂ = CFOR_f, wherein R_f is a C₁-C₆ (per)fluoroalkyl group, preferably CF₃, C₂F₅, C₃F₇;

(e) (per)fluoro-oxy-alkylvinylethers of formula CF₂ = CFOX, wherein X is a C₁ -C₁₂ ((per)fluoro)-oxyalkyl comprising catenary oxygen atoms, e.g. the perfluoro-2-propoxypropyl group;

(f) (per)fluorodioxoles having formula :

wherein each of R_f3, R_f4, R_f5, R_f6, equal to or different from each other, is independently selected from the group consisting of fluorine atom and C₁-C₆ (per)fluoroalkyl groups, optionally comprising one or more than one oxygen atom, such as notably -CF₃, -C₂F₅, -C₃F₇, -OCF₃, -OCF₂CF₂OCF₃; preferably, perfluorodioxoles;

(g) (per)fluoro-methoxy-vinylethers (MOVE, hereinafter) having formula:

        CF₂=CFOCF₂OR_f2

wherein R_f2 is selected from the group consisting of C₁-C₆ (per)fluoroalkyls; C₅ -C₆ cyclic (per)fluoroalkyls; and C₂-C₆ (per)fluorooxyalkyls, comprising at least one catenary oxygen atom; R_f2 is preferably -CF₂CF₃ (MOVE1); -CF₂CF₂OCF ₃ (MOVE2); or -CF₃ (MOVE3);

(h) C₂-C₈ non-fluorinated olefins (OI), for example ethylene and propylene; and

(2) TFE-based copolymers, in which TFE is copolymerized with monomer (CSM), as above detailed, and at least one additional comonomer selected from the group consisting of (c), (d), (e), (g), (h) and (i) as above detailed

9. The composition (C) of anyone of the preceding claims, wherein the content of iodine and/or bromine in the fluoroelastomer (A) is at least 0.05 % wt, preferably of at least 0.06 % weight, with respect to the total weight of fluoroelastomer (A), with respect to the total weight of fluoroelastomer (A) and/or not exceeding 7 % wt, more specifically not exceeding 5 % wt, or even not exceeding 4 % wt, with respect to the total weight of fluoroelastomer (A).

10. The composition (C) according to anyone of the preceding claims, wherein fluoroelastomer (A) is selected from the group consisting of those having iodine cure sites comprised as terminal groups and having following monomers composition (in mol %, with respect to the total moles of recurring units) :

(i) tetrafluoroethylene (TFE): 50-80 %; (per)fluoroalkylvinylethers (PAVE): 15 50 %; monomer (CSM): 0.1-10 %; bis-olefin (OF): 0-5 %;

(ii) tetrafluoroethylene (TFE): 20-70 %; (per)fluoro-methoxy-vinylethers (MOVE): 25-75 %; (per)fluoroalkylvinylethers (PAVE): 0-50 %; monomer (CSM) 0.1-10 %; bis-olefin (OF): 0-5 %.

11. The composition (C) of anyone of the preceding claims, wherein the peroxide (O) is selected from the group consisting of di(alkyl/alryl) peroxides, including for instance di-tert-butyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, di(t-butylperoxyisopropyl)benzene, dicumyl peroxide; diacyl peroxides, including dibenzoyl peroxide, disuccinic acid peroxide, di(4-methylbenzoyl)peroxide, di(2,4-dichlorobenzoyl)peroxide, dilauroyl peroxide, decanoyl peroxide; percarboxylic acids and esters, including di-tert-butyl perbenzoate, t-butylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane; peroxycarbonates including notably di(4-t-butylcyclohexyl)peroxydicarbonate, di(2-phenoxyethyl)peroxydicarbonate, bis[1,3-dimethyl-3-(tert-butylperoxy)butyl] carbonate, t-hexylperoxyisoproprylcarbonate, t-butylperoxyisopropylcarbonate.

12. The composition of anyone of the preceding claims, wherein the amount of peroxide (O) in the composition (C) is of 0.1 to 5 phr, preferably of 0.2 to 4 phr, relative to 100 weight parts of fluoroelastomer (A).

13. A method for fabricating shaped articles comprising curing the composition (C), according to anyone of the preceding claims.

14. Cured articles obtained from the composition (C) of anyone of claims 1 to 12, said cured articles being selected from the group consisting of sealing articles, including O(square)-rings, packings, gaskets, diaphragms, shaft seals, valve stem seals, piston rings, crankshaft seals, cam shaft seals, and oil seals, piping and tubings, in particular flexible hoses or other items, including conduits for delivery of hydrocarbon fluids and fuels.

Ansprüche

1. Fluorelastomerzusammensetzung [Zusammensetzung (C)], umfassend:

- mindestens ein Fluorelastomer [Fluorelastomer (A)], umfassend 0,1 bis 10,0 Mol-% Wiederholungseinheiten, die sich von mindestens einem Härtungsstellen enthaltenden Monomer mit mindestens einer Nitrilgruppe [Monomer (CSM)] ableiten, bezogen auf die gesamten Mole von Wiederholungseinheiten, und umfassend Iod- und/oder Brom-Härtungsstellen in einer solchen Menge, dass der I- und/oder Br-Gehalt 0,04 bis 10,0 Gew.-%, bezogen auf das Gesamtgewicht von Fluorelastomer (A), beträgt;

- mindestens ein organisches Peroxid [Peroxid (O)];

- mindestens ein Bisolefin [Bisolefin (OF)] der allgemeinen Formel:

wobei R₁, R₂, R₃, R₄, R₅ und R₆, die gleich oder voneinander verschieden sind, für H oder C₁-C₅-Alkyl stehen, Z für einen linearen oder verzweigten C₁-C₁₈-Kohlen(wasser)stoffrest (einschließlich Alkylen- oder Cycloalkylenrest), der gegebenenfalls Sauerstoffatome enthält und vorzugsweise mindestens teilweise fluoriert ist, oder einen (Per)fluor(poly)oxyalkylenrest mit einer oder mehreren kettenständigen Etherbindungen stehen, und

- mindestens eine Verbindung [Verbindung (A)] aus der Gruppe bestehend aus:

(A-1) Bisamino(thio)phenol-Verbindungen [Aminophenol (AP)] der Formel:

wobei:

- A für eine Bindung, -SO₂-, -O-, -C(O)- oder ein (Fluor)alkyl mit 1 bis 10 Kohlenstoffatomen (speziell ein Perfluoralkyl mit 1 bis 10 Kohlenstoffatomen) steht;

- E, das bei jedem Auftreten gleich oder verschieden ist, für Sauerstoff oder Schwefel, vorzugsweise Sauerstoff, steht und wobei die Amino- und -EH-Gruppen austauschbar in ortho-, meta- oder para-Positionen bezüglich der Gruppe A stehen; und

(A-2) aromatischen Tetraaminverbindungen [Amin (TA)] der Formel:

wobei:

- A' für eine Bindung, -SO₂-, -O-, -C(O)- oder ein (Fluor)alkyl mit 1 bis 10 Kohlenstoffatomen (speziell ein Perfluoralkyl mit 1 bis 10 Kohlenstoffatomen) steht;

- die Reste R_N, die gleich oder voneinander verschieden sind, jeweils für ein Wasserstoffatom oder eine C₁-C₁₂-Kohlenwasserstoffgruppe, vorzugsweise eine Arylgruppe, stehen und

- die Aminogruppen austauschbar in ortho-, meta- oder para-Positionen bezüglich der Gruppe A' stehen.

2. Zusammensetzung (C) nach Anspruch 1, wobei das Aminophenol (A) aus der Gruppe bestehend aus 4,4'-[2,2,2-Trifluor-1-(trifluormethyl)ethyliden]bis(2-aminophenol) und 4,4'-Sulfonylbis(2-aminophenol) ausgewählt ist und/oder wobei das Amin (TA) aus der Gruppe bestehend aus 3,3'-Diaminobenzidin und 3,3',4,4'-Tetraaminobenzophenon und einer Verbindung der Formel:

ausgewählt ist.

3. Zusammensetzung (C) nach einem der vorhergehenden Ansprüche, wobei die Menge von Verbindung (A) in der Zusammensetzung (C) mindestens 0,1 phr, vorzugsweise mindestens 0,2 phr, weiter bevorzugt mindestens 0,5 phr, und/oder höchstens 10 phr, vorzugsweise höchstens 6 phr, bevorzugt höchstens 5 phr, bezogen auf 100 Gewichtsteile Fluorelastomer (A), beträgt.

4. Zusammensetzung (C) nach einem der vorhergehenden Ansprüche, wobei das Bisolefin (OF) aus der Gruppe bestehend aus denjenigen, die den Formeln (OF-1), (OF-2) und (OF-3) entsprechen, ausgewählt ist:

(OF-1)

wobei j für eine ganze Zahl zwischen 2 und 10, vorzugsweise zwischen 4 und 8, steht, und R1, R2, R3 und R4, die gleich oder voneinander verschieden sind, für H, F oder eine C_1-5-Alkyl- oder -(Per)-fluoralkylgruppe stehen;

(OF-2)

wobei die Reste A, die gleich oder voneinander verschieden sind, bei jedem Auftreten jeweils unabhängig aus F, Cl und H ausgewählt sind; die Reste B, die gleich oder voneinander verschieden sind, bei jedem Auftreten jeweils unabhängig aus F, Cl, H und OR_B ausgewählt sind, wobei R_B für einen verzweigten oder geradkettigen Alkylrest, der teilweise, weitgehend oder vollständig fluoriert oder chloriert sein kann, steht; E für eine gegebenenfalls fluorierte zweiwertige Gruppe mit 2 bis 10 Kohlenstoffatomen, in die Etherbindungen eingeschoben sein können, steht; vorzugsweise E für eine -(CF₂)_m-Gruppe steht, wobei m für eine ganze Zahl von 3 bis 5 steht; ein bevorzugtes Bisolefin vom (OF-2)-Typ F₂C=CF-O-(CF₂)₅-O-CF=CF₂ ist;

(OF-3)

wobei E, A und B die gleiche Bedeutung wie oben definiert haben; R5, R6 und R7, die gleich oder voneinander verschieden sind, für H, F oder eine C_1-5-Alkyl- oder -(Per)fluoralkylgruppe stehen.

5. Zusammensetzung (C) nach Anspruch 4, wobei das Bisolefin (OF) der Formel CH₂=CH(CF₂)₆-CH=CH₂ entspricht.

6. Zusammensetzung (C) nach einem der vorhergehenden Ansprüche, wobei die Menge von Bisolefin (OF) der Zusammensetzung (C) mindestens 0,1 phr, vorzugsweise mindestens 0,2 phr, weiter bevorzugt mindestens 0,5 phr, und/oder höchstens 10 phr, vorzugsweise höchstens 6 phr, weiter bevorzugt höchstens 5 phr, bezogen auf 100 Gewichtsteile Fluorelastomer (A), beträgt.

7. Zusammensetzung nach einem der vorhergehenden Ansprüche, wobei das Fluorelastomer (A) zusätzlich zu Wiederholungseinheiten, die sich von Monomer (CSM) gemäß obigen Angaben ableiten, Wiederholungseinheiten, die sich von mindestens einem (per)fluorierten Monomer ableiten, umfasst, wobei das (per)fluorierte Monomer allgemein aus der Gruppe bestehend aus

- C₂-C₈-Fluor- und/oder -Perfluorolefinen, wie Tetrafluorethylen (TFE), Hexafluorpropen (HFP), Pentafluorpropylen und Hexafluorisobutylen;

- hydrierten C₂-C₈-Monofluorolefinen, wie Vinylfluorid;

- 1,2-Difluorethylen, Vinylidenfluorid (VDF) und Trifluorethylen (TrFE);

- (Per)fluoralkylethylenen der Formel CH₂=CH-R_f0, worin R_f0 für ein C₁-C₆- (Per) fluoralkyl oder ein C₁-C₆-(Per)fluoroxyalkyl mit einer oder mehreren Ethergruppen steht;

- Chlor- und/oder Brom- und/oder Iod-C₂-C₆-fluorolefinen, wie Chlortrifluorethylen (CTFE);

- Fluoralkylvinylethern der Formel CF₂=CFOR_f1, worin R_f1 für ein C₁-C₆-Fluor- oder -Perfluoralkyl, z.B. -CF₃, -C₂F₅, -C₃F₇, steht;

- Hydrofluoralkylvinylethern der Formel CH₂=CFOR_f1, worin R_f1 für ein C₁-C₆-Fluor- oder -Perfluoralkyl, z.B. -CF₃, -C₂F₅, -C₃F₇, steht;

- Fluoroxyalkylvinylethern der Formel CF₂=CFOX₀, worin X₀ für ein C₁-C₁₂-Oxyalkyl oder ein C₁-C₁₂-(Per)fluoroxyalkyl mit einer oder mehreren Ethergruppen steht, insbesondere (Per)fluormethoxyvinylethern der Formel CF₂=CFOCF₂OR_f2, worin R_f2 für ein C₁-C₆-Fluor- oder -Perfluoralkyl, z.B. -CF₃, -C₂F₅, -C₃F₇ oder ein C₁-C₆-(Per)fluoroxyalkyl mit einer oder mehreren Ethergruppen, wie -C₂F₅-O-CF₃, steht;

- funktionellen Fluoralkylvinylethern der Formel CF₂=CFOY₀, worin Y₀ für ein C₁-C₁₂-Alkyl oder -(Per)fluoralkyl oder ein C₁-C₁₂-Oxyalkyl oder ein C₁-C₁₂- (Per) fluoroxyalkyl steht, wobei die Gruppe Y₀ eine Carbon- oder Sulfonsäuregruppe in ihrer Säure-, Säurehalogenid- oder Salzform umfasst;

- (Per)fluordioxolen der Formel:

worin R_f3, R_f4, R_f5 und R_f6, die gleich oder voneinander verschieden sind, jeweils unabhängig voneinander für ein Fluoratom, ein C₁-C₆-Fluor- oder -Per(halogen)fluoralkyl, das gegebenenfalls ein oder mehrere Sauerstoffatome enthält, z.B. -CF₃, -C₂F₅, -C₃F₇, -OCF₃, -OCF₂CF₂OCF₃, stehen;
ausgewählt ist.

8. Zusammensetzung (C) nach einem der vorhergehenden Ansprüche, wobei das Fluorelastomer (A) aus

(1) auf VDF basierenden Copolymeren, in denen VDF mit Monomer (CSM) gemäß obigen Angaben und mindestens einem zusätzlichen Comonomer aus der Gruppe bestehend aus

(a) C₂-C₈-Perfluorolefinen, wie Tetrafluorethylen (TFE), Hexafluorpropylen (HFP);

(b) wasserstoffhaltigen C₂-C₈-Olefinen, wie Vinylfluorid (VF), Trifluorethylen (TrFE), Hexafluorisobuten (HFIB), Perfluoralkylethylenen der Formel CH₂=CH-R_f, worin R_f für eine C₁-C₆-Perfluoralkylgruppe steht;

(c) C₂-C₈-Fluorolefinen mit mindestens einem von Iod, Chlor und Brom, wie Chlortrifluorethylen (CTFE);

(d) (Per)fluoralkylvinylethern (PAVE) der Formel CF₂=CFOR_f, worin R_f für eine C₁-C₆-(Per) fluoralkylgruppe, vorzugsweise -CF₃, -C₂F₅, -C₃F₇, steht;

(e) (Per)fluoroxyalkylvinylethern der Formel CF₂=CFOX, worin X für ein C₁-C₁₂-((Per)fluor)oxyalkyl mit kettenständigen Sauerstoffatomen, z. B. die Perfluor-2-propoxypropylgruppe, steht;

(f) (Per)fluordioxolen der Formel:

worin R_f3, R_f4, R_f5 und R_f6, die gleich oder voneinander verschieden sind, jeweils unabhängig voneinander aus der Gruppe bestehend aus einem Fluoratom und C₁-C₆-(Per) fluoralkylgruppen, die gegebenenfalls ein oder mehr als ein Sauerstoffatom enthalten, wie insbesondere -CF₃, -C₂F₅, -C₃F₇, -OCF₃, -OCF₂CF₂OCF₃, ausgewählt sind; vorzugsweise Perfluordioxolen;

(g) (Per)fluormethoxyvinylethern (im Folgenden MOVE) der Formel:

        CF₂=CFOCF₂OR_f2,

worin R_f2 aus der Gruppe bestehend aus C₁-C₆-(Per)fluoralkylgruppen, cyclischen C₅-C₆- (Per) - fluoralkylgruppen und C₂-C₆-(Per)fluoroxyalkylgruppen mit mindestens einem kettenständigen Sauerstoffatom steht; R_f2 vorzugsweise für -CF₂CF₃ (MOVE1); -CF₂CF₂OCF₃ (MOVE2) oder -CF₃ (MOVE3) ausgewählt ist;

(h) nichtfluorierten C2-C8-Olefinen (OI), beispielsweise Ethylen und Propylen;
copolymerisiert ist; und

(2) auf TFE basierenden Copolymeren, in denen TFE mit Monomer (CSM) gemäß obigen Angaben und mindestens einem zusätzlichen Comonomer aus der Gruppe bestehend aus (c), (d), (e), (g), (h) und (i) gemäß obigen Angaben copolymerisiert ist;
ausgewählt ist.

9. Zusammensetzung (C) nach einem der vorhergehenden Ansprüche, wobei der Gehalt von Iod und/oder Brom in dem Fluorelastomer (A) mindestens 0,05 Gew.-%, vorzugsweise mindestens 0,06 Gew.-%, bezogen auf das Gesamtgewicht von Fluorelastomer (A), bezogen auf das Gesamtgewicht von Fluorelastomer (A), beträgt und/oder nicht mehr als 7 Gew.-%, spezieller nicht mehr als 5 Gew.-% oder sogar nicht mehr als 4 Gew.-%, bezogen auf das Gesamtgewicht von Fluorelastomer (A), beträgt.

10. Zusammensetzung (C) nach einem der vorhergehenden Ansprüche, wobei Fluorelastomer (A) aus der Gruppe bestehend aus denjenigen mit Iod-Härtungsstellen, die als Endgruppen enthalten sind, und der folgenden Monomerenzusammensetzung (in Mol-%, bezogen auf die gesamten Mole von Wiederholungseinheiten) ausgewählt sind:

(i) Tetrafluorethylen (TFE): 50-80 %; (Per)fluoralkylvinylethern (PAVE): 15-50 %; Monomer (CSM): 0,1-10 %; Bisolefin (OF): 0-5 %;

(ii) Tetrafluorethylen (TFE): 20-70 %; (Per)fluormethoxyvinylethern (MOVE): 25-75 %; (Per)fluoralkylvinylethern (PAVE): 0-50 %; Monomer (CSM): 0,1-10 %; Bisolefin (OF): 0-5 %.

11. Zusammensetzung (C) nach einem der vorhergehenden Ansprüche, wobei das Peroxid (O) aus der Gruppe bestehend aus Di(alkyl/aryl)peroxiden einschließlich beispielsweise Di-tert-butylperoxid, 2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexan, Di(t-butylperoxyisopropyl)benzol, Dicumylperoxid; Diacylperoxiden einschließlich Dibenzoylperoxid, Dibernsteinsäureperoxid, Di(4-methylbenzoyl)-peroxid, Di(2,4-dichlorbenzoyl)peroxid, Dilauroylperoxid, Decanoylperoxid; Percarbonsäuren und Percarbonsäureestern einschließlich Di-tert-butylperbenzoat, t-Butylperoxy-2-ethylhexanoat, 1,1,3,3-Tetramethylethylbutylperoxy-2-ethylhexanoat, 2,5-Dimethyl-2,5-di(2-ethylhexanoylperoxy)hexan; Peroxycarbonaten einschließlich insbesondere Di(4-t-butylcyclohexyl)peroxydicarbonat, Di(2-phenoxyethyl)peroxydicarbonat, Bis[1,3-dimethyl-3-(tert-butylperoxy)butyl]carbonat, t-Hexylperoxyisopropylcarbonat, t-Butylperoxyisopropylcarbonat ausgewählt ist.

12. Zusammensetzung nach einem der vorhergehenden Ansprüche, wobei die Menge von Peroxid (O) in der Zusammensetzung (C) 0,1 bis 5 phr, vorzugsweise 0,2 bis 4 phr, bezogen auf 100 Gewichtsteile Fluorelastomer (A), beträgt.

13. Verfahren zur Herstellung von Formkörpern, bei dem man die Zusammensetzung (C) gemäß einem der vorhergehenden Ansprüche härtet.

14. Gehärtete Artikel, erhalten aus der Zusammensetzung (C) nach einem der Ansprüche 1 bis 12, wobei die gehärteten Artikel aus der Gruppe bestehend aus Dichtungsartikeln einschließlich O(Quadrat)-Ringen, Packungen, Dichtungen, Diaphragmen, Wellendichtungen, Ventilschaftdichtungen, Kolbenringen, Kurbelwellendichtungen, Nockenwellendichtungen und Öldichtungen, Rohren und Schläuchen, insbesondere flexiblen Schläuchen oder anderen Gegenständen einschließlich Leitungen zur Beförderung von Kohlenwasserstofffluiden und Kraftstoffen ausgewählt sind.

Revendications

1. Composition fluoroélastomère [composition (C)] comprenant :

- au moins un fluoroélastomère [fluoroélastomère (A)] comprenant de 0,1 à 10,0 % en moles de motifs répétitifs issus d'au moins un monomère contenant un site de durcissement possédant au moins un groupe nitrile [monomère (CSM)], par rapport aux moles totales de motifs répétitifs, et comprenant des sites de durcissement de type iode et/ou brome en une quantité telle que la teneur en I et/ou Br est de 0,04 à 10,0 % en poids, par rapport au poids total de fluoroélastomère (A) ;

- au moins un peroxyde organique [peroxyde (O)] ;

- au moins une bis-oléfine [bis-oléfine (OF)] possédant la formule générale :

R₁, R₂, R₃, R₄, R₅ et R₆, identiques ou différents les uns des autres, étant H ou C_1-5-alkyle ; Z étant un radical (hydro)carboné linéaire ou ramifié en C_1-18 (y compris un radical alkylène ou cycloalkylène), contenant éventuellement des atomes d'oxygène, préférablement au moins partiellement fluoré, ou un radical (per)fluoro(poly)oxyalkylène comprenant une ou plusieurs liaisons éther caténaires,
et

- au moins un composé [composé (A)] choisi dans le groupe constitué par :

(A-1) des composés de type bis-amino(thio)phénol [aminophénol (AP)] de formule :

- A étant une liaison, -SO₂-, -O-, -C(O)-, ou un (fluoro)alkyle de 1 à 10 atome(s) de carbone (spécifiquement un perfluoroalkyle de 1 à 10 atome(s) de carbone) ;

- chacun parmi E, identiques ou différents en chaque occurrence, étant oxygène ou soufre, préférablement oxygène, et les groupes amino et -EH étant de manière interchangeable en position ortho, méta ou para par rapport au groupe A ; et

(A-2) des composés de type tétramine aromatique [amine (TA)] de formule :

- A' étant une liaison, -SO₂-, -O-, -C(O)-, (fluoro)alkyle de 1 à 10 atome(s) de carbone (spécifiquement un perfluoroalkyle de 1 à 10 atome(s) de carbone) ;

- chacun parmi R_N, identiques ou différents les uns des autres, étant un atome d'hydrogène ou un groupe hydrocarboné en C_1-12, préférablement un groupe aryle ; et

- les groupes amino étant de manière interchangeable en position ortho, méta ou para par rapport au groupe A'.

2. Composition (C) selon la revendication 1, l'aminophénol (A) étant choisi dans le groupe constitué par le 4,4'-[2,2,2-trifluoro-1-(trifluorométhyl)-éthylidène]bis(2-aminophénol) et le 4,4'-sulfonylbis(2-aminophénol) ; et/ou l'amine (TA) étant choisie dans le groupe constitué par la 3,3'-diaminobenzidine, et la 3,3',4,4'-tétraminobenzophénone et un composé de formule :

3. Composition (C) selon l'une quelconque des revendications précédentes, la quantité de composé (A) dans la composition (C) étant d'au moins 0,1, préférablement d'au moins 0,2, plus préférablement d'au moins 0,5 ; et/ou d'au plus 10 phr, préférablement d'au plus 6 phr, plus préférablement d'au plus 5 phr, par rapport à 100 parties en poids de fluoroélastomère (A).

4. Composition (C) selon l'une quelconque des revendications précédentes, la bis-oléfine (OF) étant choisie dans le groupe constitué par celles se conformant aux formules (OF-1), (OF-2), et (OF-3) :

j étant un entier compris entre 2 et 10, préférablement entre 4 et 8, et R₁, R2, R3, R4, identiques ou différents les uns des autres, étant H, F ou un groupe alkyle ou (per)fluoroalkyle en C_1-5 ;

chacun de A, identiques ou différents les uns des autres et en chaque occurrence, étant indépendamment choisi parmi F, Cl, et H ; chacun de B, identiques ou différents les uns des autres et en chaque occurrence, étant indépendamment choisi parmi F, Cl, H et OR_B, R_B étant un radical alkyle à chaîne ramifiée ou linéaire qui peut être partiellement, sensiblement ou complètement fluoré ou chloré ; E étant un groupe divalent possédant 2 à 10 atomes de carbone, éventuellement fluoré, qui peut être intercalé par des liaisons éther ; préférablement E étant un groupe -(CF₂)_m-, m étant un entier de 3 à 5 ; une bis-oléfine préférée du type (OF-2) étant F₂C=CF-O- (CF₂)₅-O-CF=CF₂,

E, A et B possédant la même signification que définie ci-dessus ; R5, R6, R7, identiques ou différents les uns des autres étant H, F ou un groupe alkyle ou (per)fluoroalkyle en C_1-5.

5. Composition (C) selon la revendication 4, la bis-oléfine (OF) se conformant à la formule : CH₂=CH-(CF₂)₆-CH=CH₂.

6. Composition (C) selon l'une quelconque des revendications précédentes, la quantité de bis-oléfine (OF) dans la composition (C) étant d'au moins 0,1, préférablement d'au moins 0,2, plus préférablement d'au moins 0,5 et/ou d'au plus 10 phr, préférablement d'au plus 6 phr, plus préférablement d'au plus 5 phr, par rapport à 100 parties en poids de fluoroélastomère (A).

7. Composition selon l'une quelconque des revendications précédentes, le fluoroélastomère (A) comprenant des motifs répétitifs issus d'au moins un monomère (per) fluoré, en plus des motifs répétitifs issus du monomère (CSM), tel que détaillé ci-dessus, ledit monomère (per)fluoré étant généralement choisi dans le groupe constitué par :

- des fluorooléfines et/ou des perfluorooléfines en C_2-8, telles que le tétrafluoroéthylène (TFE), l'hexafluoropropène (HFP), le pentafluoropropylène, et l'hexafluoroisobutylène ;

- des monofluorooléfines hydrogénées en C_2-8, telles que le fluorure de vinyle ;

- le 1,2-difluoroéthylène, le fluorure de vinylidène (VDF) et le trifluoroéthylène (TrFE) ;

- des (per)fluoroalkyléthylènes se conformant à la formule CH₂=CH-R_f0, dans laquelle R_f0 est un (per) fluoroalkyle en C_1-6 ou un (per) fluorooxyalkyle en C_1-6 possédant un ou plusieurs groupes éther ;

- des chloro- et/ou bromo- et/ou iodo-C_2-6-fluorooléfines, comme le chlorotrifluoroéthylène (CTFE) ;

- des fluoroalkylvinyléthers se conformant à la formule CF₂=CFOR_f1 dans laquelle R_f1 est un fluoroalkyle ou un perfluoroalkyle en C_1-6, par ex. -CF₃, -C₂F₅, -C₃F₇ ;

- des hydrofluoroalkylvinyléthers se conformant à la formule CH₂=CFOR_f1 dans laquelle R_f1 est un fluoroalkyle ou un perfluoroalkyle en C_1-6, par ex. -CF₃, -C₂F₅, -C₃F₇ ;

- des fluoro-oxyalkylvinyléthers se conformant à la formule CF₂=CFOX₀, dans laquelle X₀ est un oxyalkyle en C_1-12, ou un (per) fluorooxyalkyle en C_1-12 possédant un ou plusieurs groupes éther ; en particulier des (per)fluoro-méthoxy-vinyléthers se conformant à la formule CF₂=CFOCF₂OR_f2 dans laquelle R_f2 est un fluoroalkyle ou un perfluoroalkyle en C_1-6, par ex. -CF₃, -C₂F₅, -C₃F₇ ou un (per) fluorooxyalkyle en C_1-6 possédant un ou plusieurs groupes éther, comme -C₂F₅-O-CF₃ ;

- des fluoro-alkylvinyléthers fonctionnels se conformant à la formule CF₂=CFOY₀, dans laquelle Y₀ est un alkyle ou un perfluoroalkyle en C_1-12, ou un oxyalkyle en C_1-12 ou un (per) fluorooxyalkyle en C_1-12, ledit groupe Y₀ comprenant un groupe acide carboxylique ou acide sulfonique, dans sa forme acide, halogénure d'acide ou sel ;

- des (per)fluorodioxoles, de formule :

chacun de R_f3, R_f4, R_f5, R_f6, identiques ou différents les uns des autres, étant indépendamment un atome de fluor, un fluoroalkyle ou un per(halogéno)fluoroalkyle en C_1-6, éventuellement comprenant un ou plusieurs atomes d'oxygène, par ex. -CF₃, -C₂F₅, -C₃F₇,-OCF₃, -OCF₂CF₂OCF₃.

8. Composition (C) selon l'une quelconque des revendications précédentes, le fluoroélastomère (A) étant choisi parmi :

(1) des copolymères à base de VDF, dans lesquels le VDF est copolymérisé avec un monomère (CSM), tel que détaillé ci-dessus, et au moins un comonomère supplémentaire choisi dans le groupe constitué par

(a) des perfluorooléfines en C_2-8, telles que le tétrafluoroéthylène (TFE), l'hexafluoropropylène (HFP) ;

(b) des oléfines en C_2-8 contenant de l'hydrogène telles que le fluorure de vinyle (VF), le trifluoroéthylène (TrFE), l'hexafluoroisobutène (HFIB), des perfluoroalkyléthylènes de formule CH₂=CH-R_f, R_f étant un groupe perfluoroalkyle en C_1-6 ;

(c) des fluorooléfines en C_2-8 comprenant au moins l'un parmi iode, chlore et brome, telles que le chlorotrifluoroéthylène (CTFE) ;

(d) des (per)fluoroalkylvinyléthers (PAVE) de formule CF₂=CFOR_f, R_f étant un groupe (per)fluoroalkyle en C_1-6, préférablement CF₃, C₂F₅, C₃F₇ ;

(e) des (per)fluoro-oxy-alkylvinyléthers de formule CF₂=CFOX, X étant un ((per) fluoro)-oxyalkyle en C₁-C₁₂ comprenant des atomes d'oxygène caténaires, par ex. le groupe perfluoro-2-propoxypropyle ;

(f) des (per)fluorodioxoles possédant la formule :

chacun de R_f3, R_f4, R_f5, R_f6, identiques ou différents les uns des autres, étant indépendamment choisi dans le groupe constitué par un atome de fluor et des groupes (per) fluoroalkyle en C_1-6, éventuellement comprenant un ou plusieurs atomes d'oxygène, tels que notamment : -CF₃, -C₂F₅, -C₃F₇, -OCF₃,-OCF₂CF₂OCF₃ ; préférablement, des perfluorodioxoles ;

(g) des(per)fluoro-méthoxy-vinyléthers (MOVE, ci-après) possédant la formule :

        CF₂=CFOCF₂OR_f2

R_f2 étant choisi dans le groupe constitué par les (per) fluoroalkyles en C_1-6 ; les (per) fluoroalkyles cycliques en C_5-6 ; et les (per) fluorooxyalkyles en C_2-6, comprenant au moins un atome d'oxygène caténaire ; R_f2 étant préférablement-CF₂CF₃ (MOVE1) ; -CF₂CF₂OCF₃ (MOVE2) ; ou -CF₃ (MOVE3) ;

(h) des oléfines non fluorées en C_2-8 (OI), par exemple l'éthylène et le propylène ; et

(2) des copolymères à base de TFE, dans lesquels le TFE est copolymérisé avec un monomère (CSM), tel que détaillé ci-dessus, et au moins un comonomère supplémentaire choisi dans le groupe constitué par (c), (d), (e), (g), (h) et (i) tel que détaillé ci-dessus.

9. Composition (C) selon l'une quelconque des revendications précédentes, la teneur en iode et/ou en brome dans le fluoroélastomère (A) étant d'au moins 0,05 % en poids, préférablement d'au moins 0,06 % en poids, par rapport au poids total du fluoroélastomère (A), par rapport au poids total du fluoroélastomère (A) et/ou n'excédant pas 7 % en poids, plus spécifiquement n'excédant pas 5 % en poids, ou même n'excédant pas 4 % en poids, par rapport au poids total de fluoroélastomère (A) .

10. Composition (C) selon l'une quelconque des revendications précédentes, le fluoroélastomère (A) étant choisi dans le groupe constitué par ceux possédant des sites de durcissement de type iode en tant que groupes terminaux et possédant la composition de monomères suivante (en % en moles, par rapport aux moles totales de motifs répétitifs) :

(i) tétrafluoroéthylène (TFE) : 50 à 80 % ; (per)fluoroalkylvinyléthers (PAVE) : 15 à 50 % ; monomère (CSM) : 0,1 à 10 % ; bis-oléfine (OF) : 0 à 5 % ;

(ii) tétrafluoroéthylène (TFE) : 20 à 70 % ; (per)fluoro-méthoxy-vinyléthers (MOVE) : 25 à 75 % ; (per)fluoroalkylvinyléthers (PAVE) : 0 à 50 % ; monomère (CSM) : 0,1 à 10 % ; bis-oléfine (OF) : 0 à 5 %.

11. Composition (C) selon l'une quelconque des revendications précédentes, le peroxyde (O) étant choisi dans le groupe constitué par les di(alkyl/aryl)peroxydes, y compris par exemple le di-tert-butylperoxyde, le 2,5-diméthyl-2,5-bis(tert-butylperoxy)hexane, le di(t-butylperoxyisopropyl)benzène, le dicumylperoxyde; les diacylperoxydes, y compris le dibenzoylperoxyde, le disuccinoylperoxyde, le di(4-méthylbenzoyl)peroxyde, le di(2,4-dichlorobenzoyl)peroxyde, le dilauroylperoxyde, le décanoylperoxyde ; les acides et esters percarboxyliques, y compris le di-tert-butylperbenzoate, le t-butylperoxy-2-éthylhexanoate, le 1,1,3,3-tétraméthyléthylbutyl peroxy-2-éthylhexanoate, le 2,5-diméthyl-2,5-di(2-éthylhexanoylperoxy)hexane ; les peroxycarbonates, y compris notamment le di(4-t-butylcyclohexyl)peroxydicarbonate, le di(2-phénoxyéthyl)peroxydicarbonate, le bis[1,3-diméthyl-3-(tert-butylperoxy)butyl]carbonate, le t-hexylperoxyisoproprylcarbonate, le t-butylperoxyisopropylcarbonate.

12. Composition selon l'une quelconque des revendications précédentes, la quantité de peroxyde (O) dans la composition (C) étant de 0,1 à 5 phr, préférablement de 0,2 à 4 phr, par rapport à 100 parties en poids de fluoroélastomère (A) .

13. Procédé pour la fabrication d'articles façonnés comprenant le durcissement de la composition (C), selon l'une quelconque des revendications précédentes.

14. Articles durcis obtenus à partir de la composition (C) selon l'une quelconque des revendications 1 à 12, lesdits articles durcis étant choisis dans le groupe constitué par des articles d'étanchéité, y compris des anneaux (carrés) en O, des garnitures, des garnitures d'étanchéité, des diaphragmes, des boîtes d'étanchéité, des joints de tige de valve, des anneaux de piston, des joints d'étanchéité de vilebrequin, des joints d'étanchéité d'arbre à came, et des joints d'étanchéité d'huile, des tuyaux et des tubes, en particulier des tuyaux flexibles ou d'autres objets, y compris des conduites pour la distribution de fluides hydrocarbures et de carburants.